Blade Sharpener

ABSTRACT

A device for sharpening lawnmower and sod cutting blades is provided. The blade sharpener provides a rotatable blade bed that can be used to safely adjust the grinding attack angle without exposing the operator to the moving grinding wheel. The blade bed of the present invention can be quickly adjusted over a range of different sharpening angles and is adapted for honing both right and left-sided blades.

FIELD OF THE INVENTION

This invention pertains to a device for sharpening blades, particularly blades for residential and commercial lawn mowers, sod cutters, and the like. The blade sharpener of the present invention provides a rotatable blade bed that that can quickly be adjusted over a range of different sharpening angles, which allows greater efficiency in sharpening multiple blades of varying honing angles. The blade sharpener of the present invention is also adapted for honing both right-side and left-side blades with only a simple adjustment to the blade bed base and the grinder yoke.

BACKGROUND OF THE INVENTION

There are numerous examples of blade grinders in the prior art. However, there is not a sharpening device that can quickly and easily accommodate a variety of blade sharpening angles while also allowing easy adaption between right and left-sided blades. The advantage of the present invention is that one single sharpening device can now be used across a wide range of residential and commercial cutting blades without the need for time-consuming refitting and jury-rigging of the sharpening device.

Prior art devices generally combine rotational sharpening functions around a single point. This is an impractical approach to repetitive sharpening operations of differing blades because, the device is generally unwieldy to adjust due to the difficulty of isolating one axis for rotational adjustment while the other axes are moving. In addition, prior art devices fail to accommodate for right and left-side blade interoperability with blades of varying honing angles. For example, in U.S. Pat. No. 9,102,031, issued to Page, a sharpening device is disclosed that suffers from these disadvantages. The Page device has a 3-way pivot point located above an unmoving blade bed. The device is inadequate for repetitive sharpening of blades with varying honing angles because of the difficulty in adjusting the rotational attack of the grinder relative to the honing surface of the blade. Further, the device does not easily operate between set angles of grinding, which is a necessary feature for efficient blade sharpening operations. In addition, the immovable blade bed of Page cannot accommodate both right and left-sided blades.

Other prior art devices suffer similar disadvantages. U.S. Pat. No. 7,967,666 to Messner discloses a blade sharpening apparatus with a pivot connector where the grinder itself is rotated around an axis perpendicular to the blade length. The Messner device also allows translational movement along the blade length but it does not allow for easy relocation of the grinder away from the blade surface for the purpose of interchanging blades. Further, the Messner device is unable to easily accommodate both right and left-sided blades.

U.S. Pat. No. 7,918,715 to Clark et al. discloses a device that can sharpen both clockwise and counterclockwise blades (right and left-sided blades) by rotating the blade bed a full 180 degrees. However, the blade bed is not otherwise adjustable for accepting blades of various hone angles. In order to process blades of varying angles, an operator of the Clark device must make careful adjustments to the attack angle of the grinder. Again, this is a cumbersome approach for repetitive sharpening operations.

U.S. Pat. No. 6,761,623 to Baker discloses a blade sharpening device that sharpens blades at a predetermined angle. The Baker device has a means of blade support that allows for the proper positioning of the blade with respect to the sharpening mechanism so as to generate the correct sharpening angle for the sharpening of the blade. However, the device cannot accommodate the simple interchange of right and left-sided blades. Furthermore, adjustment of the honing angle is cumbersome, with a hand operated crank set forth as the preferred method for rotating the blade bed. The Baker invention does not provide for rapid adjustment of blade angles as now provided by the present invention.

It is a feature of the present invention to provide a blade sharpener that can accommodate rapid and easy adjustment of the sharpening angle through an easily adjustable blade bed.

It is still another feature of the present invention to provide a blade sharpener that has a grinding apparatus that is freely moveable in a wide range of motion while locking the attack grinding angle.

It is still another feature of the present invention to provide a blade sharpener that can easily be switched between right and left-sided blades.

It is yet another feature of the present invention to provide a blade sharpener that allows for safe operation of the grinding apparatus during both right and left-sided sharpening operations.

It is yet another feature of the present invention to provide a blade sharpener that supports quick, repetitive sharpening of blades with varying honing angles.

It is still another feature of the present invention to provide a blade sharpener that is suitable for commercial operations.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates a front view of a blade sharpener of the present invention arranged for sharpening a long blade.

FIG. 2 illustrates a top perspective view of a blade sharpener of the present invention arranged for sharpening a long blade.

FIG. 3 illustrates a front view of a blade sharpener of the present invention arranged for sharpening a short blade.

FIG. 4 illustrates a top perspective view of a blade sharpener of the present invention arranged for sharpening a short blade.

It will be appreciated that the drawings are illustrative and not limiting of the scope of the invention which is defined by the appended claims. The embodiments shown accomplish various aspects and objects of the invention. It is appreciated that it is not possible to clearly show each element and aspect of the invention in a single figure, and as such, multiple figures are presented to separately illustrate the various details of the invention in greater clarity.

DETAILED DESCRIPTION OF THE INVENTION

Reference will now be made in detail to the presently preferred embodiments of the invention. There are also representative examples of the invention illustrated in the accompanying drawings. Throughout the following detailed description, the same reference numeral refers to the same elements in all figures.

Now referring to the drawings, and first to FIG. 1, a blade sharpener in accordance with the present invention is illustrated. The blade sharpener comprises a base 10 that supports the unit during operation. Base 10 comprises a base plate 12 that is preferably a flat piece of metal that can provide stability to the unit during operation. In an optional embodiment, legs (not shown), can be attached to base plate 12 so the unit can be placed directly on a floor. When base plate 12 is not attached to legs, the unit can be placed on a desk, bench, or other supporting surface that is in direct contact with the base plate. Base 10 further comprises post 14 and riser 16. Post 14 serves to provide an elevated attachment point for flex arm 30, which is discussed below. Riser 16 provides additional stability to post 14 during operation of the unit and is attached at a first end to base plate 12 and at an opposing end to post 14. Mounting studs 18 (shown in FIG. 4) may be located in similar 2-pair configurations on base plate 12 and provide securing points for selective securement of blade bed assembly 20, as further explained below. Blade bed assembly 20 is secured to base plate 12 by placing engagement holes in the assembly over studs 18 and threading mounting nuts 19 onto the studs.

The blade sharpener of the present invention further comprises blade bed assembly 20, that holds the mower blade in a position for sharpening. The assembly comprises blade bed base 22 and blade bed 23. As shown in FIG. 2, in one arrangement base 22 is formed in an L-shaped configuration with holes for accepting insertion of mounting studs 18 from base plate 12 such that base 22 can be secured to base plate 12 by tightening mounting nuts 19 onto mounting studs 18. Blade bed 23 has a generally flat surface that is rotatable around the longitudinal axis of a thru bolt or thru rod (not shown) that is inserted through blade bed base 22. In one embodiment, rotation of blade bed 23 is achieved through selective adjustment of a ratchet arm 24 that can be used to quickly adjust the angle of blade bed 23 in relation to blade bed base 22. In a preferred embodiment of the invention, ratchet arm 24 is configured for engagement with preset detents in either the thru bolt or blade bed base 22 such that blade bed 23 can be easily positioned at specific angles. In one embodiment, the angles selectable by ratchet arm 24 are the common sharpening angles of 30° and 40°. In another embodiment, the selectable angles are even multiples between 30° and 40°, inclusive. In yet another embodiment, ratchet arm 24 can be used to rotate blade bed 23 in a continuous motion around the thru bolt.

A holding clamp 25 which is rotatable is affixed to blade bed 23 for securely holding blade 60. Holding clamp 25 can be any type of device that can secure blade 60 so that it does not shift or move during the sharpening procedure. In one embodiment, holding clamp 25 is a vice-type clamp that can be locked into holding position and easily released into an unlocked position when desired. Studs 26 are affixed to blade bed 23 to provide support to blade 60 and to prevent downward movement of blade 60 during the sharpening operation. Blade bed 23 also is provided with shoulder bolt holes 28 for receiving shoulder bolts 27. As shown in FIG. 3, in one embodiment of the invention shoulder bolt holes 28 are offset to accommodate placement of angled ends from short blades. There may also be two sets of shoulder bolt holes 28, with each set position on opposite ends of blade bed 23. In this manner, the blade sharpener of the present invention can be used to easily switch between right and left-sided blades by changing by 180° the orientation of blade bed assembly 20. When a short blade is sharpened, the blade 60 may be positioned with a single stud 26 providing vertical support and two offset shoulder bolts 27 providing horizontal support. This arrangement is particularly useful for short blades with angled ends, as shown in FIG. 3. For this type of short blade, the offset nature of shoulder bolts 27 combined with the vertical support of stud 26 works to resist the upward motion of the blade caused by downward pressure exerted on blade 60 during the sharpening procedure.

As discussed above, the present invention provides for easy switching between right and left-sided blades. The dual sets of shoulder bolt holes 28 and the placement of studs 26 on opposite ends of blade bed 23 provide a mirrored configuration such that blade bed 23 can be repositioned 180°. Referring to FIG. 4, in one embodiment mounting studs 18 are provided in two pairs placed on opposite sides of base plate 12. Blade bed assembly 20 can be switched between each pair of mounting studs 18 to accommodate both right and left-sided operations. In another embodiment, blade bed assembly 20 can be mounted to base plate 12 using a swivel attachment that can be secured between two positions 180° apart. This is a preferred configuration because of the ease of switching blade bed assembly 20 between the right and left-handed positions.

The blade sharpener of the present invention further comprises flex arm 30, which is a parallel arm assembly. Gas springs 32 are placed in each arm segment so that flex arm 30 can be extended and held in position without need for counter weights or counter-balancing springs. Flex arm 30 is attached to post 14 using swivel mount 34, which allows a wide range of rotational motion around the axis of rotation defined by the longitudinal length of post 14. The free rotation enabled by flex arm 30 and swivel mount 34 allow operation of the grinder 40 in a wide range of motion and is particularly helpful for quickly moving grinder 40 out of the way while exchanging blades for sharpening. In addition, a particular feature of the present invention, is the limitation of movement of grinder 40 to two dimensions in relation to blade 60. Because the angle of grinding attack is set by the rotational movement of blade bed 23 through adjusting ratchet arm 24 and not through rotational movement of flex arm 30 in a third dimension, the present grinder is better suited to discrete changes of grinding attack. Ratchet arm 24 is located near the grinding operation to enable the operator to conveniently adjust the grinding attack. Further, isolating the grinding attack adjustment mechanism away from the movement of flex arm 30 is safer for the operator. When the operator wishes to adjust the grinding angle, he can swing flex arm 30 out of the way and easily adjust ratchet arm 24 to rotate blade bed 23 without exposing skin, clothing or other loose items to the spinning grinder blade 42. Prior art arrangements where the grinding attack adjustment mechanism is associated with the swing arm or the grinder itself are unsafe because the operator is more exposed to the spinning grinder when adjusting the attack angle.

As mentioned above, the present invention also comprises a grinder 40 for sharpening blade 60. Grinder 40 comprises grinding blade 42, body 44, handle 46, and safety guard 47. Grinding blade 42 may be an abrasive disk or a beveled plate-type surface that offers an incremental approach to the grinding action. Body 44 houses the motor of grinder 40, and also provides a general surface for moving or holding the grinder in position. In addition, handle 46 provide an additional gripping location for guiding and moving the grinder through its range of motion. Handle 46 is bolted through body 44 of grinder 40 and is secured in place with a nut (not shown) located on the opposite side of the body. Safety guard 47 is placed over one half of grinding blade 42 in a direction opposite honing edge 62 of blade 60. The safety guard prevents loose items and skin from inadvertent contact with grinding blade 42. It also catches grinding debris from spinning grinding blade 42 and directs it down and away from the operator. Grinder 40 also comprises face tabs 48 on a top portion of the grinder that assist in holding grinder 40 in a steady position in yoke 50, as explained below.

The present invention further comprises a yoke 50 for attaching grinder 40 to flex arm 30. As shown in FIG. 2, yoke 50 is U-shaped with opposing handle holes 57 for receiving the thru bolt portion of grinder handle 46. Attachment rod 56 is rotatable and affixed to the end of flex arm 30 and tab slots 54 are designed to receive face tabs 48 of grinder 40. In this manner, grinder 40 can be securely attached to flex arm 30. A set screw 52 is inserted into attachment rod 56 to arrest rotational movement of grinder 40 about an axis defined by the longitudinal length of attachment rod 56.

During operation of the blade sharpener on a right-handed blade, the operator can set blade bed 23 at a 15° angle away from the line formed along the length of flex arm 30. In this manner, the operator can easily see grinding blade 42 acting on honing edge 62 of blade 60. To switch to a left-handed blade, the operator simply moves blade bed assembly 20 by 180° to an opposite position, places the blade on the opposite end of the now swiveled blade bed assembly and adjusts the grinder 40 angle using set screw 52 to an opposite 15° angle away from the line formed along the length of flex arm 30. This allows grinding operations to continue without needing to remove safety guard 47. Without adjusting the angle of grinder 40 from its right-sided position, safety guard 47 would interfere with the sharpening action on left-sided blades. Thus, the present invention provides for multi-sided blade honing without needing to disable or remove safety guard 47.

The present invention may be embodied in other specific forms without departing from its spirit or essential characteristics. The described embodiments are to be considered in all respects only as illustrative and not restrictive. The scope of the invention is, therefore, indicated by the appended claims rather than by the foregoing description. All changes that come within the meaning and range of equivalency of the claims are to be embraced within their scope. 

1. A blade sharpener comprising: a blade bed assembly comprising a blade bed base, an inclinable blade bed having blade supports located on opposing sides of said blade bed, and means for securing a blade to be sharpened to said blade bed, wherein said blade bed is moveable between two opposing 180° positions; a flex arm configured for two-dimensional movement about said blade to be sharpened; and a sharpener connected to said flex arm; wherein the angle of sharpening attack between a blade to be sharpened and said sharpener is primarily determined by the inclination of said blade bed and further wherein said flex arm is not substantially rotatable about said angle of sharpening.
 2. The blade sharpener of claim 1, wherein said blade bed further comprises offset shoulder supports located in a mirrored arrangement on opposing sides of said blade bed.
 3. The blade sharpener of claim 1, wherein said blade bed assembly further comprises a ratchet arm preconfigured for selective inclination of said blade bed in set angles of sharpening attack between a blade to be sharpened and said sharpener.
 4. The blade sharpener of claim 3, wherein said set angles of sharpening attack are 30° and 40°. 